(19)
(11) EP 0 999 479 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
17.09.2003 Bulletin 2003/38

(43) Date of publication A2:
10.05.2000 Bulletin 2000/19

(21) Application number: 99121574.0

(22) Date of filing: 29.10.1999
(51) International Patent Classification (IPC)7: G03G 15/01, G03G 15/00
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 02.11.1998 JP 31221498
14.12.1998 JP 35493598
22.12.1998 JP 36408098

(71) Applicant: Sharp Kabushiki Kaisha
Osaka-shi Osaka (JP)

(72) Inventors:
  • Taka, Kyosuke
    Nara-shi, Nara (JP)
  • Takahashi, Kazunobu
    Nara-shi, Nara (JP)
  • Sakagami, Hidekazu
    Sakurai-shi, Nara (JP)
  • Manabe, Nobuo
    Yamatokoriyoma-shi, Nara (JP)
  • Harada, Yoshikazu
    Nara-shi, Nara (JP)
  • Fukutome, Shoichi
    Yamatokoriyama-shi, Nara (JP)

(74) Representative: Müller - Hoffmann & Partner 
Patentanwälte, Innere Wiener Strasse 17
81667 München
81667 München (DE)

   


(54) Image forming apparatus


(57) Assuming the photosensitive drum for black as a reference, the phase of the adjacent photosensitive drum for cyan leads by about 60 deg. Similarly, the phase of the photosensitive drum for magenta leads by about 120 deg., and the phase of the photosensitive drum for yellow leads by about 180 deg. The phase of each photosensitive drum is shifted to thereby make it possible to shift the phase of driving unevenness. By shifting the phase, even the distance between adjoining transfer positions corresponding to the image forming stations is set shorter than the circumference of the photosensitive drum, the variation of each photosensitive drum due to driving unevenness with respect to the printing medium passing through the transfer position can be kept congruent with the others.






Search report